Medium optimization to improve the flocculation rate of a novel compound bioflocculant, CBF-256, using response...

A novel compound bioflocculant, CBF-256, was obtained using three bacterial strains, Bacillus sp., Enterobacter sp., and Aeromonas sp., which were screened from activated sludge of a printing and dyeing wastewater treatment plant. Response surface methodology was employed to optimize the fermentation medium dosage to improve the flocculation rate of CBF-256, which increased from 69.00% to 82.65%. In addition the yield of the compound bioflocculant increased from 2.31 g·L(-1) to 2.84 g·L(-1). The flocculating efficiency distribution of the components of the culture broth indicated that the supernatant was the most effective component in the flocculation process. Fourier transform infrared spectroscopy and scanning electron microscopy were used to analyze the fermentation medium and composite bacteria. The compound flocculants were produced easily, and during the flocculation process, all the flocculation ingredients settled down in the remaining sludge along with the bacteria screened from the activated sludge, without causing secondary pollution.